Salinity Meters

[lysol]

My new oakton supposedly measures salinity, PH, conductivity and temperature...

How exactly do salinity and TDS / conductivity interrelate and how can salinity measurements be used in growing?

Would TDS lower as salinity rised or would salinity rise while TDS remained the same? How will having this feature help me if at all? Is it only really useful when using sodium filters and such or can I use it in everyday use for any purpose?

I realize it is mentioned in bigToke's sticky but I don't understand how it differs / relates to TDS.

 

[EvilTwin]

Hi lysol,
That's interesting. Salinity in common usage is a measure of NaCl (table salt) in water. But in chemistry, the term "salts" has a broader definition.

I'd try out the salinity scale and see how it changes during the course of a grow. It could be that you may be able to roughly measure nutrients salts and guage the need for res change. Just a thought.

Also, it certainly could come in handy measuring coco runoff water when it's new to determine of it's clean of salts.

Not all of your disolved solids are salts...so the salinity reading should be lower.

Have fun with it and report back if you find anything useful to do with it.
ET

 

[lysol]

I guess I will have to do some experiments, I have fox farms full line and the parts for lucas. I could set up some test buckets and such and see how different kinds of waters / nutes generate salt over time

 

[lysol]

My tap water measures 150ppm TDS, it measures 140ppm salinity
My nutrient mixed using RO water only reads 950ppm TDS, it measures 1.5ppm salinity

big difference

edit: my bad.. thats ppt, parts per thousand, and I had to switch it to .5 mode not .7 mode, salts = TDS + some amount.

But I must admit I'm a little confused, aren't salts "solids"?

Also my truncheon shows 950ppm, the oakton shows 1.1 ppt = 1100 ppm, calling them to see whats going on. Maybe the factory TDS calibration is off... dunno.

Ok got my answer. manual reads "once temperature is set no other paramamaters to set as temperature is common to all", the tech support person however told me "the manual is wrong"

So yeah I need to get TDS ref. solution or I could just approximate it and calibrate based off a solution with known tds such as using my
truncheon and then calibrating the oakton to what the truncheon reads.

A really great TDS FAQ http://www.coleparmer.com/techinfo/techinfo.asp?htmlfile=Conductivity_faq.htm&ID=79#anchor0

7. How do I calibrate my meter for TDS if my dissolved solids are not the same as those in the calibration solutions sold in the Cole-Parmer catalog?

Making your own standard will yield the most accurate results. This is done by formulating a mixture of salts in relative proportions that simulate the solution to be tested, then dissolving the mixture into distilled water. This should be done according to the following formula:

1 mg salt mixture/liter of distilled water = 1 ppm TDS,
or in other words,
X ppm TDS = X mg of salts + one liter of distilled water.

Remember that "X mg of salts" is the number of milligrams of a mixture of salt of which proportions simulate your test solution, not X milligrams of each salt in the mixture. An appropriate value for "X" is determined by the following rule:
Choose a ppm value for a calibrated solution as close as possible to the expected ppm values of the test solutions. If the ppm content of the test solution is expected to vary a great deal, it is best to choose a ppm value for the calibrated solution in the upper 1/3 of the TDS indicator's measurement range.

12. How should I store my conductivity electrode?

Rinse it in tap water when you are finished using it. You can store your electrode either wet or dry. If it is stored dry you will need to recondition the electrode before use. Go to Top
​

13. How do I condition a probe?

Place the probe in a standard solution or tap water and have power running to the probe. Let the probe soak for 30 minutes to 1 hour unless otherwise specified. Go to Top
​

14. What is the difference between conductivity and salinity?

The probe is the same for conductivity and salinity, but in a salinity meter a correction factor is applied to the reading. The correction factor takes the conductivity reading and converts it to ppm of a specific salt. The salt varies from manufacturer to manufacturer. Some use NaCl while others use CaCO3.​

​

The way im applying this is just mixing up a batch of lucas at 0-8-16 in a 5 gallon bucket and setting it to 950ppm then, that way my meter is calibrated to lucas and I don't have to buy TDS reference fluid

 

[lysol]

Oh shit, fresh batch of lucas = 950 on both meters,

bucket with plant reads 950 on truncheon 810 on the Oakland. Does Truncheon suck or something? Going to have to start recording 2 methods of EC & PH and see wtf is going on now. x4 buckets = 8 readings x2 a day = 16 wtf im gonna be so busy now lol

Both meters read my tap water correct, and the oakland is 1 point calibration. I could record a video if you think im doing something wrong. Im literally going with both meters from 1 bucket to the next

bucket A
is 950 on both,

on bucket B
the oakland reads 850
the bluelabs trunch 950

ok i just realize 1 param does vary, temp.. by like 2F, the truncheon must compensate incorrectly / slowly ( and yea am letting it sit for a minute to "adjust" which is a pain in the first place anyways ). If I had to do it again I would have skipped the truncheon, it works nice but this 4 in 1 is the same price and its like scientific grade, the truncheon is like a novelty mixing wand to me

I let the truncheon sit another 5 or 6 minutes its now reading 900ppm... lol what bunk in the minute it took me to edit my post just now it jumped back up to 950..

I also notice when I do readings sometimes it comes in really low like 300 or 400 ppm and then takes like 30 seconds and it jumped up to the higher level readings. Do you think this is a warranty issue or their meters just suck? I rinse off after every single reading and clean it weekly per their instructions to a T, the meter is not 3 months old.

Bucket B has .1 ppt or 100ppm less salt ( bucket with plant ) according to the Oakton as opposed to bucket A ( the fresh batch which reads salts at 1100ppm )

So my plant is eating salts? Dunno half this is over my head, I just learned another scale to measure salts ( correction NOT SALTS CONDUCTIVITY ) in smaller increments is micro semens µS http://en.wikipedia.org/wiki/Siemens_(unit) lol

Later on I will try boiling some water and eye dropping it into bucket A to raise its temp to equal bucket B and re-test.

 

[EvilTwin]

Hi Lysol,
Sheesh, you've been a busy guy. Yes, salts are dissolved solids. I sure don't know why you're getting such difference with your two meters. I have a Bluelab and am happy with it...but it has some limitations, but for quick and dirty res management, it's perfect. Fits my style. And I know a lot of good growers (online) who use the Blueline. it'll be interesting to see the results once you get a reference solution. All sounds rather complicated.
Good luck with that...
ET

 

[FreezerBoy]

My tap water measures 150ppm TDS, it measures 140ppm salinitySo yeah I need to get TDS ref. solution or I could just approximate it and calibrate based off a solution with known tds such as using my
truncheon and then calibrating the oakton to what the truncheon reads.

There's no such thing as a TDS meter. TDS requires chemical analysis. Your "TDS" meter (note the quotes) measures EC and EC only. And then it lies to you. If want a "bigger" number use an EC meter that measures µS/cm (microsiemens per centimeter) rather than the more common mS/cm (millisiemens per centimeter) 1mS/cm=1000µS/cm.

While I think you're too fixated on numbers, if you're going to fixate, do it with numbers that mean something.

....add....

Does Truncheon suck or something?

I'd trust the truncheon. "PPM" and "TDS" are bullshit.

 

[Wait...What?]

Its a folly to take a tds/ec reading from one day to the next and add back the 'missing ppm' since you have no idea what the plant took up or why.

EC/TDS meters are of no value in this context. Find a feeding schedule you like and go with it. The only way to know what your plants are short on, to adjust the nutrient mix, is to take a leaf sample and send it to the lab. You aren't mixing your nutrient solution from raw elements or their compounds anyway so you don't have any way of adjusting. So don't worry about it.

I don't know if you've encountered the "Lucas" formula yet, but you may or maynot have noticed that its the same ratio from the first day of veg all the way through. Ponder that for a while. The formula doesn't change from the first day of veg, until you cut the micro in mid-to-late flower.

The plants leaves will tell you way more than a meter will anyway.

 

[lysol]

There's no such thing as a TDS meter. TDS requires chemical analysis. Your "TDS" meter (note the quotes) measures EC and EC only. And then it lies to you.

Well yeah I know what you are saying, both meters are reporting EC x 500 though, so just know I meant conductivity not TDS, sorry, but same question still applies, how can CONDUCTIVITY be 1.8ec on both meters in 1 bucket and then be .1ec different on another bucket w/ same ec. I would use micro seimens so that I could be semantic but just easier to state it in ec x 500 = ppm ( even though we all know "tds meter" is a joke ). Both meters read 950ppm in a fresh batch of lucas which means they measuring the same conductivity since they both are configured to use the same conversation rates. ( the oakland is really configurable like that, it even has an adjustable "temperature coefficient" which could be why it is reporting the conductivity different )

While I think you're too fixated on numbers, if you're going to fixate, do it with numbers that mean something.

Not really fixated on #s, I think there is reason to be concerned if my meter reports EC climbing or dropping that I don't act wrong

I'd trust the truncheon. "PPM" and "TDS" are bullshit.

Hmm both meters report in conductivity as well as tds

Its a folly to take a tds/ec reading from one day to the next and add back the 'missing ppm' since you have no idea what the plant took up or why.

True good point, but if EC is climbing or dropping I can do a change out and lower or raise the concentration. I know the plant dont care about conductivity, but it does care about a stable environment, right???

EC/TDS meters are of no value in this context. Find a feeding schedule you like and go with it. The only way to know what your plants are short on, to adjust the nutrient mix, is to take a leaf sample and send it to the lab. You aren't mixing your nutrient solution from raw elements or their compounds anyway so you don't have any way of adjusting. So don't worry about it.

Well I think we are thinking in a different context

I don't know if you've encountered the "Lucas" formula yet, but you may or maynot have noticed that its the same ratio from the first day of veg all the way through. Ponder that for a while. The formula doesn't change from the first day of veg, until you cut the micro in mid-to-late flower.

yeah I posted this earlier...

The way im applying this is just mixing up a batch of lucas at 0-8-16 in a 5 gallon bucket and setting it to 950ppm then, that way my meter is calibrated to lucas and I don't have to buy TDS reference fluid

I understand lucas tailored the ratios to our plant so I am gonna stop using my foxfarms and use all lucas,

The plants leaves will tell you way more than a meter will anyway.

Well I know it is possible to grow without taking it to the point where the leafs are visibly stressed. Freezerboy showed me a page from his diary, over time you could see PH dropping and EC rising, he would do a change out within days of this happening and try a lower EC, if it was still happening he would change out again and yet another ec, mean time the pics in his journal you see nothing but green healthy foliage... by the time my plants are stressed its a crap shoot because it could have been something I did a week ago for all I know

I'm not really lazy at all, I will change out my nutes daily to keep ratios in check if thats what it takes to get me good pot, but in a different context I think it is important to find out wether the bucket stayed at 950ppm or dropped to 810ppm overnight ya know, that big of a drop overnight and I would be wise to do a changeout and up the strength. ( by the way I know not to act on more than 1 day's worth of data, as FB said it takes 3 points to make a line )

I'll try to get by on as much common sense as possible and I will be forming charts to see how the different #s on the different meters change over time and making notes of if the plant is improving or not. Not trying to adjust N-P-K individually by any means at all, its just if I make notes I can keep things more stable, I know the ec is for me not the plant Even if EC didnt really drop a changeout shouldn't do much harm, I'd basically be simulating a sort of drain to waste system I would think ( kind of. )

I don't want to be feeding up and stressing the plant just because my temps moved down during the course of a week or something mundane I could overlook

 

[FreezerBoy]

Hmm both meters report in conductivity as well as tds

No, they do not. TDS requires chemical analysis. You're measuring EC and EC alone, no matter what the meter says. How is multiplying by 500, 640, 650, 700, 768 or any other lie, easier that using the truth without any multiplication at all?

If your meters don't agree, throw the Oakton in the trash. The Truncheon is a tool, the Oakton is a toy.

 

[lysol]

Report in, not measure.

and how is a meter that requires no calibration a tool while a meter that does get calibrated is a toy? The Oakton measures temperature digitally, the truncheon marketing lied to me when they said it was "temperature compensated", I have to let the meter sit, the Oakton does not...

but until I get to the bottom of it no conclusions can be drawn. It is possible either one of the meters is faulty I suppose.

Edit: got to the bottom, when I calibrated to 950ppm turns out the 2 minutes i let the truncheon sit was not sufficient, that solution was really 1000ppm ( the truncheon was reporting 950ppm which I set the oakton to, so the oakton was performing correctly when it told me bucket B is 810ppm, because I told it to report 50ppm lower since the truncheon lied )

after I let the truncheon sit for like hours. the "temp compensation" on it really sucks. I think will get the tds calibration for the oakton and sell the bluelabs to someone who doesnt seem to have as many growing problems as me.

And Yeah I know TDS is not PPM I've been told a million times. accuracy to .1 ec is good for sharing nutrient strengths between different growers, it does not meet my needs for seeing the difference between yesterday the day before and today though.

 

[FreezerBoy]

Report in, not measure.

It does not report in TDS. It doesn't report anything. TDS requires chemical analysis. "TDS" meters kill the report and pass on lies in the form of nonsense.

I did serious homework on this after my fan debacle saw $300 flushed down the drain for nothing. The EC Truncheon is the most trusted meter we have. Why would you trust a toy that you know is incapable of telling the truth?

 

[lysol]

It does not report in TDS. It doesn't report anything. TDS requires chemical analysis. "TDS" meters kill the report and pass on lies in the form of nonsense.

I did serious homework on this after my fan debacle saw $300 flushed down the drain for nothing. The EC Truncheon is the most trusted meter we have. Why would you trust a toy that you know is incapable of telling the truth?

Personally I dont "trust" any meter per se, because you guys have taught me to trust the plant over some bullshit #, however, to suite my fancy I would rather know the quantitative difference between 2 measurements that although may be semantically incorrect in a literal sense, vary on a constant linear scale. If I know both #s vary on a constant scale I could set my meter to report conductivity via approximated TDS as EC x 99999999999999999, as long as I know to divide by 99999999999999999 to get the real EC that was measured.

And both meters report in TDS & conductivity. So I'm not sure what makes the one a toy, by your definition they would both have to be toys then since the truncheon is "lying" with their ppm conversion that is printed on the meter itself eh?

That's what I meant by measured vs reporting.

All I'm saying is I'd rather know my TDS went up by "10 lysol make believe units" each day for 7 consecutive days,
rather then waiting until the end of the week and my meter telling me it went up 10 lysol units in 1 day.

In the latter situation I would think my PH is about to swing due to over feeding and probably take corrective action where none was needed ( because I'm new to the hobby ), whereas if I can see its moving up in nominal amounts I would not over react.


Metaphor

I have an object that has a mass of 1kg on earth, it still has a mass of 1kg on the moon, even though it would weight 1/6th as much.

My meter's manual & manufacturer both tell me the meter works by measuring conductivity and then multiplying that by a constant ( which I can set to whatever I want... 499, 501 whatever ). Any "ppm" my meter reports can be divided by this constant to obtain EC.

Let's say now that Russia disagrees with us on the Moons gravity and uses 1/10th of mass to approximate weight instead.

Lets say you took a 1Kg ( in mass ) object and asked both Russia and USA to approximate the weight, USA says 1/6Kg, Russia would say 1/10Kg

Thats the same thing as taking a 1.0ec solution and asking 2 meters that disagree to approximate the ppm, a USA meter might say 500ppm while an Australian might say 700ppm

Even though they are both different conversions, the #s are still highly predictable.

For instance If I knew Russians thought gravity was 1/10th that of Earth's on the Moon, and they approximated an object weighed 100Kg on the moon, and was given their conversion rates for the approximation, I can effectively say that object DOES weigh 1,000Kg on Earth with a mass of 1,000Kg.

Now let's assume in the above example both parties were wrong about the Moon's gravity and it was really 1/5th, so no one got the weight of the object on the Moon correct, However dispute these weight values that are full of lies, I can still derive that the mass of the object is 1 Kg accurately and predictably each and every time I get an approximate weight from a Russian by dividing his estimate by the constant he used to obtain it.

If my meter is reporting a 'estimated TDS' of 500ppm but its really 9,000ppm, then whatever, but if I am _guaranteed_ it is coming up with this fluff by measuring EC and multiplying by 500, then I can guarantee that my solution has an EC of 1.1

I just prefer to write 500ppm, 510ppm, 520ppm, 540ppm, 575ppm, etc... rather then 1ec, 1.02ec, 1.04, 1.08, 1.15

I could use EC x 1,000 if I wanted and say 1,000ppm, 1,200ppm, etc.. it doesnt matter because I'm using it as an intermediary # to obtain EC. It would probably make sense just to measure in EC in the first place, but that would also entail giving up some ability to discern small daily trends because the truncheon reports +/- .1 ec, the Oakland reports in EC +/- .002 ( I just have to divide and ignore the litle ppm sign, not a big deal. ), 250x increase in accuracy


Anyways

this is just personal preference. I am sure both meters are trust worthy in terms of measuring EC, if operated properly. Both lie about ppm according to your definition of "report" lol, the benefit to me, personally, as a new hobbyist is the Oakland does not require 2 minutes to temperature compensate, it is 4 meters in one for $50 less, it is 250x more granular in it's measurements. The truncheon has its benefits too and it is a fine meter I will continue to use, it just sucks at temperature compensating.

for $130 they could have put a digital read out display at least accurate to .01 ec, they could have put a digital temperature sensor to eliminate length temperature acclimation. I'm just saying to me it seems like bluelabs is manufacturing these meters for what amounts to zilch in terms of cost, for instance a temperature probe is $0.20 a unit in bulk and would not have complicated the microprocessor much more. displaying in increments of .01 or even .05 ec on a nice backlit digital readout probably would have been very feasible for them to do for the $130 MSRP



Anyways I am just trying to take some of your theories to a new level, you should be flattered ( your own words ) if EC down PH up means feed up, and EC up PH down means feed down, whats so wrong about knowing PH +/- .01 instead of relying on drops, and knowing EC +/- .001 instead of +/- .1

I guess why you keep correcting me is that my statement might and I mean might be construed as implying actual ppm can be obtained from EC, but in the last week I think I have started 3 threads related to EC / meters, etc.. and must have had 10-15 post and keep saying the same thing..


but If I know a meter is measuring EC at Y1, timesing that by X and reporting it [incorrectly] as Y2 ppm, I can derive:

Y1 (EC) = Y2 (ppm) / X ( 500 )

I can not derive in any way the ppm from either value of Y, obviously

I also understand deriving the conductivity does not tell me to feed up or down alone, but I can use it as a warning sign to change out to a solution with a known ratio...........

In that context it is helpful to know my solution went up or down by some amount of units, even if the name I call those units means something different to other people.. it is useful if and only if the approximation formula is known, for most "TDS meters" it is known.


Hopefully we can keep this objective, I started the subjective name calling of the meters and I apologize, neither meters are novelties both are tools with their own pros and cons.

 

[lysol]

my fan debacle saw $300 flushed down the drain for nothing.

Hey what do you mean by fan debacle? And perhaps my post would make more sense if I stated my core reasoning behind wanting more resolution. I wish to plot graphs in a spreadsheet program instead of writing notes by hand. The more specifically I measure the less my little line looks like a square wave, the more information I have collected. I can always round the #s later if I want but I can't go back in time and wonder what happened that week I fucked up my plant

 

[delta9nxs]

hey,lysol

hey,lysol

your brain must be hurtin'. but, you are a fast study and think on your own.

unless you are doing peer reviewed research actual accuracy is not that critical. nor is what format your particular meter reads ec in. like hand grenades, close is good enough. what my meters do for me is give me a relative starting point. i know there is probably an ongoing error, but as long as the error is repeatable it doesn't matter. i am still allowed to see relative changes and make corrections.

the keeping of records is bad from a legal point of view but excellent for long term progress. by going over mine i can see patterns or trends.

endeavor to persevere

 

[lysol]

your brain must be hurtin'. but, you are a fast study and think on your own.

unless you are doing peer reviewed research actual accuracy is not that critical. nor is what format your particular meter reads ec in. like hand grenades, close is good enough. what my meters do for me is give me a relative starting point. i know there is probably an ongoing error, but as long as the error is repeatable it doesn't matter. i am still allowed to see relative changes and make corrections.

the keeping of records is bad from a legal point of view but excellent for long term progress. by going over mine i can see patterns or trends.

endeavor to persevere

Right, anyone doubting my logic can read http://en.wiktionary.org/wiki/normalize. Always keep files on a memory stick or sd card encrypted and locked in a safe bolted to the floor in the same room as the grow. if anyone gets my sd card im already fucked anyways

* OF COURSE this is not applicable in the context of grower A sharing his ppm values with grower b, only grower A comparing his own ppm to his own ppm ( different dates & times )


THANK YOU FOR THE KIND WORDS

 

[delta9nxs]

salinity

salinity

hey, here is something i thought you might want to see. it's from big tokes "basic water chemistry". one of the stickies above. the first time i saw it i got an audible "click" between the ears. a great illustration depicting these relationships.

Each triangle is part of the whole (salinity) and represents either total Ca and Mg free ions, free carbonates and bicarbonates and pH. Where they overlap is the area that that triangle affects the overlapping triangle.

The red area would represent CaCO3 (calcium carbonate - lime) and/or MgCO3 (dolomite lime) and this would precipitate out of solution and therefore not affect pH.

The green area would be free Ca and Mg ions and would have a contributing pH of neutral.

The yellow area would represent carbonates and bicarbonates and have a contributing pH of 7-9.

 

[lysol]

Ok, I know that conductivity only "reads" a certain % of different elements, for some it is 40% for others its 60%, etc...

So to read this chart, I would find my PH along the bottom, and the colored areas are an approximation of the conductivity that would be registered on a salinity meter? I'm a little confused. I read the thread but I admit parts went over my head, I probably need to read up on wikipedia and return to that thread when I understand a little more i dunno

 

[lysol]

I finally got my tds calibration solution. Result... bluelabs truncheon shows 1400ppm when it is put into 1500ppm solution. I let it sit for 1 minute, 2 minutes, 5 minutes and it still reads exactly 1400, and of course now there is no way to calibrate this thing.

My oakton was even more off but since it has a calibration mode it now reads 1500ppm in 1500ppm reference solution. The truncheon has proved to be a little inaccurate and I am going to seek warranty service on it I guess.